The Neurochemistry Core provides a service function for standard analytical techniques. Microdialysis is used extensively to monitor changes in extracellular fluid neurotransmitter and metabolite concentrations in multiple time points in each experiment. The concentration of amino acids, including glutamate, aspartate glycine and GABA, will be measured by HPLC. Another assay used extensively is the conversion of radiolabeled arginine in radiolabeled citrulline a marker of nitric oxide production. This production is also applied to microdialysis samples in which labeled arginine is measured in the dialysate. The Core will serve by performing radioimmunoassays for estradiol, progesterone and cyclic GMP. By pooling all of these analytical techniques into a common core, personnel trained in benchwork biochemistry can generated high quality results in a cost-efficient manner. Moreover, the analytical workload within individual projects can fluctuate from year-to-year. Pooling the workload from all projects will result in a more efficient utilization of personnel time. Lastly, the Core facility provides a resource for introducing new assays into the laboratory when a study may require unforseen measurements to strengthen the conclusions of the study.